Intercommunicating system



June 27, 1950 K. I. B. LEG

ERTH 2,512,834

INTERCOMMUNICATING SYSTEM Filed Dec.

4 Sheets-Sheet l A Wm: 41f] 6%) June 27, 1950 I 1, LEGERTH 2,512,834

INTERCOMMUNICATING SYSTEM Filed Dec. 19, 1946 I 4 Sheets-Sheet 3 June 27, 1950 K, I, B. L EGERTH 2,512,834

INTERCOMMUNICATING SYSTEM Filed Dec. 19, 1946 4 Sheets-Sheet 4 0 766 w A95 w 786 F7 B C l/Zzmfw:

Patented June 27, 1950 PATENT Applidatin-fiecember 19,

1946 Serjgi 1%., 717,27 6

Iii Sweden J'anuary 24, 1946. 1 1 Claims'.- (01. 1 79-'-38);

The present invention relates to an intercom municatin-g system in'cltrd-ing a pl-i-i iality ef-sepa rate' stations eachcomprising a" combined mitterand re'eeiveii andat'leasttwd amplifiers:

@ne object of the invention is to proviti'e; a system in which any of amplifiers may be used fer the connection between two' arbitrarystations.

Another object of the invention-19w provide a system in which each station need not be donnected with eeteh amplifierby means of sepa rate wires.

Other objects and advantages of the invention will be painted out and evidentto these ki l-led inthe art from the following descriptientkeiff' in connection with the accompanying drawings, wherein there shown, by wayof |i11iistratieri, a-- preferred embodiment of a system according to r the inveiition;

In the drawings:

Figure 1- is a; schematie diagram cafe-station,

Figure 2 is a schi'neti diagram of' thiee relay groupsbeltinging te a device for setting up- 2:- call;

Figure 4- is a schematm diagram finely: unitadapt'ed for selecting a, rela roup mit 66-- cupi'ed by 203111; and

Figure 5 shows at modified embddi'me'fit of a cireiiit sho'wn Fig. 3. V

Referring" to Fig. 1 the shown statien -is pro'---- vided with: a start key] and: keys 5 few caning any of' the othe'x s'tati cins belonging td= the sy'sa tern Thus; the-number of 7 saw keys- 5 aorta-- spend to the number df-"stati0ns in the sy stern minus 0116i For the-sake ofsimplieity oni keys 5 are shown' her'eli Further; there iska; re storing-key 6 andaloudsneaker i aka-usable asa; microphone.-

Eaeh: stationis provided: with'si x contacts;- in the drawing-designated a; b, c, d, e} anew; for the v connection of the station to the sYstM and with two eontactsgdesignated and: for" the connectionof th station to* the pliis and minus terminals of asource-0f current. Furtherj thereare contacts vII; vIII-ete'; to a number -oo1=ie--- spending to thenur'nbeho'f the keys ii. Finm' th'e manner of designatingit is obvious that the-stat tion showniri Fig-e l is Called I and thait 'ijhe other stations-are provided with a contact esc'hematie diagram tact m is cmmevcte'dwith the crr'espendingeb preventing circle currents'frm arising. Impulse"- In Fig. 4 there is shown a diagram of a relayunit by means of which a disengaged relaygroup A, B or C is selected. There is a separate relay arrangement having relays I5 and I6 for each group A, B and C and each relay arrangement is provided with contacts I1 and I8 which are connected with corresponding contacts in the relay-groups. cv is connected to'the relay-unit.

When the startkey is operated the contacts connected with each other will be positive for a short peniod and a circuit will be closed through the contact I9 and the operating winding (the lower winding in the figure) of the relay ISA which will be operated and is held by its holding winding (the upper winding), one terminal of said last winding being connected with the contact IIA through the one make contact of the relay. It is assumed that said contact IJA is positive. By means of the other make contact of the relay I6 a circuit will be closed through thewinding of the relay IA with the result of the latter being operated. When the relay I5A is operated the contact I9 is opened and the contacts 012 are instead connected with one terminal of the operating winding of the relay IBB through a cut-off contact of the relay I513. Thus, when the next short positive impulse passesthe contacts co the relays I53 and IE3 will be operated in substantially the same way as the relays ISA and I6A, as is described above, and the contacts at will be connected with the operating winding I60 through the closed relay contacts 28 (of I53) and 29 (of I5A) and the relay contactof the relay I50.

When the start key I in Fig. 1 is operated the contact e will be connected with the negative terminal of the source of current through the contact lo and a cut-oil contact of a cut-ofi relay 2. This relay, however, is controlled by a control relay 3, the one terminal of the winding of said latter relay being permanently connected to the negative terminal of the source of current while the other terminal of said winding is connected with the plus terminal through the contacts Id and I b, when the start key is operated. Thus, the relay 3 is operated and its contact 3a closes a circuit through the relay 2 which will cut-off the connection of the contact e with the negative terminal of the source of current. Therefore, the contact e will be negative only for a short period.

When the start key is operated the contact 022 (that is all contacts co) will be positive for a short period through the contact I b and a cut-oil contact of the relay 2 which is energized and cutsofl. the connection between the contact 01) and the plus terminal of the source of current after a very short interval.

From what is described hereinbefore it is clear that the contact e becomes negative and the contact on positive for a short period, when the start key is operated. As is seen from Fig. 4 the contact 022 is connected with the contact I8A until the cut-off contact I9- is opened, which happens just when the contact 01) becomes positive for a short period. At the next positive impulse I through the contact 00 the contact I 83 will be positive for a short period and after a further impulse the contact I8C becomes positive.

According to Fig. 3 the contact I8 is connected through the wire 20 to one terminal of the operating windings of the relays I2, the other terminals of said windings being connected to the contacts e. As mentioned hereinbefore, this con- Further, the station contact nection in fact is effected through impulse relays (not shown) of the same kind as the relays 9 for the connection of the relays 8 to the wire I0. Assuming that the relay-unit according to Fig. 4 is in the position as shown and the start key in the station I is operated the relay I2 of the relaygroup A and corresponding to the station I will be operated due to the short negative and positive impulses through the contacts at and IBA, respectively. I Therelay is then held by a holding winding one end of which is connected to the negative terminal of the source of current while the other terminal of the winding is connected to the positive terminal of the source of current through the make-contact I2a and a cut-off contact of a restoring relay I3. From Fig. 3 it will also be seen that the contact I! is connected to the positive terminal through the same cut-off contact.

By the operation of the relay I2 the loud speaker I of the station I has been connected to the input of the amplifier in the relay-group A as described hereinbefore. Simultaneously the station contact d has been connected to the wire I0 through the contact I2b, one end of the windings the winding of the relay 4 is permanently connected to the negative terminal of the source of current. During the charging of the condenser 28 the winding will be passed by a current so that the relay 4 is energized during a short interval. Thus, the relay contacts 4a and 4b are closed with the result that the contacts 0H and d are connected with the negative terminal of the source of current for a short period.

Returning to Fig. 3 it is found that the short positive impulse to the contact d causes that all relays 9 are energized for a short period. Thus, the contacts II of the relays 9 are closed so that one terminal of the operating windings of the relays 8 is connected with the negative terminal of the source of current through the wire 22 for a short period. The other terminals of said windings, however, are connected to the contacts 111, an and 22111 through wires 23. Of said contacts only the contact UII is temporarily connected to the positive terminal of the source of current with the result that only the relay 8 corresponding to the station II is operated and is held by means of a holding winding 8. By the operation of the relay 8 the loud speaker I of the station II has been connected to the output of the amplifier belonging to the relay-group A and the stations I and II have been connected with each other.

From what is described hereinbefore it is clear that when a further station in the system is calling, a connection will be set up through the relay-group B, and when yet a further station is calling a connection will be set up through the relay-group C. If any of these groups then becomes disengaged it can immediately be used for a new call from any station in the system.

In order to reverse the direction of speaking it is necessary to switch the speaking or listening keyI4. Impulses for this purpose are supplied to the key M through a wire 2| connected to the contact in the station I through a relay contact l2c. Whenthe start key I ,of the calling station is again operated, the wire 2| is connected to the positive terminal of the source of current and the key It is switched in a manner not shown but known per se.

When the call is finished therestoring key 6 of the calling station is operated with the result that the contact 30 is closed, which contact is.

included, in a manner not shown here, in the circult to the restoring relay I3 (Fig. 3). Said relay is now energized and the connection of the relays belonging to the relay-group A in question with. the positive terminal of the source of current is cut-off. The relays are set in thei normal positions and as also the connection of the contact I! with the positive terminal of the source of current is cut-ofi the relays ISA and IBA (Fig. 4) are as well de-energized. v When the key. 6 is operated also the connection between thepositive terminal of the source of current and the one terminal of the winding of the control relay 3 is cut-01f, which relay up to that time has been held by a circuit through its make contact 3b. Therefore, this relay is as well de-energized.

As a summing up of the above it can be said that in a relay-group the relays l2 serve for the connection of a calling station to the amplifier of the group, the relays 8 connect the called station to the calling station in analogy with the setting up of a call in an exchange operated by hand, while the relays 9 give impulse for assigning in advance. the setting up of a connection to an arbitrary station. Relays of the same kind as the relays 9 are preferably used; as mentioned above, for assigning in advance the setting up of a connection to a disengaged amplifier. According to Figs. 2 and 3 there is in each relay-group, A, B and C an impulse relay for each station. However, in Fig. vit is shown .howina relay-1 group-=there-is only oneimpulse relay 9 havinga .-number of -make. contacts. H-;corresponding mv the number of relays B. Qneterminalofthewindings of the relays 8 isconnected. with thenegative terminal. of the; source of .currentthroughsaid makecontacts l-l forashort period..-. .Itis. clear from the principle of. the syst m that thenumber of possible calls is. solely determined by the number of amplifiers incl-udedin the -sys-' tem and that said amplifiers maybe used for calls from all-stations of the system. If'necessary, it is relatively easy to add .-one.or. more further relay-groups having .an. amplifier to, an .already existingv system without it being necessary toadraw anynew wires to the stations. The-newrelaygroup isonly connected in parallel with the relaygroups already existing,- w H The contactsmay be arranged in another way, for instance some of them belonging to the start keyJ may be transferred to the relay 2.,, The system may be supplied by a single source of current, but itis also possibleto use-a separate source of current for each relay-group andta separate source of current for the relay-unit; If balanced two-way amplifiers are used. the. speaking ,or, listening keys may of course be omitted..

While the invention has been described ith reference to a particular system forpurposes ofillustration, .it will be understood thatvarious.

changes maybe made within, the scope of. the

following claims;

I-clairn; V .1, In an intercommunicating system,=at least three. separate stations each-comprising a combined transmitter and receiver, a number of amplifiers less than the number of stations, but at least two, a group of relays for each of said amplifiers, each of said groups comprising relaysets individually connected with one ofsaid stations, a relay-unit connected with said relay-, groups and with said stations and adapted for selecting a relay-group not occupied by a call, a start key in each station for operating said relay-unit to select an idle relay-group and for operating said selected relay-group to connect the combined transmitter and receiver of a calling station to the amplifier belonging to said relay-group, and keys in each station for calling any of the other stations, said keys actuating the relay-group selected by said relay-unit to connect the transmitter and receiver of a called station to the amplifier belonging to said relay,-

group.

2. In an intercommunicating system, a plurality' of separate stations each comprising a combined'transmitter and receiver, a source of current, at least two amplifiers, a group of relays.

for each of said amplifiers, each of said groups comprising relay-sets individually connected with one of said stations, a relay-unit connected with said relay-groups and with said stations andadapted for selecting a relay-group not occupied by a call, a connecting relay in each'of said relaysets the operating winding of which having one terminal connected to a contact in the respective station and the other terminal connected to a contact insaid relay-unit, which contact is com+ mon to all of said connectin relays in each relay-group, a start key in each station for op-.

erating said relay-unit to select an idle relaygroup and to connect its contact common to all of said connecting relays in said selected relay.- group to one terminal of said source oi'current and for connecting said contact in a calling station, which contact is connected to the wind ing of said connecting relays. tothe other. ter.-.. minal otssaid source ofcurrents-the connecting relay of-saidselected -relay-group-belonging to the relay-set connected with said calling station thereby being actuated so, that it connects the. combined-transmitter and receiver of said. call-I ing station to the amplifier belonging to said; selected relay-group,,and keys in each station for calling-any of theother stations, said keyts actuating the. relay-group selected by saidrelay-1 unitzto connect the transmitterandreceiverof. a calledstationto the amplifier belonging .to, said-relay-group.

v .3. In an intercommunicating system, va pl rality of separate station-s each. comprising a. combined transmitter and receiver, .a source of current,fat least two amplifiers, .a group. of relays:

foreach f said amplifierseach of 'saidgroups; comprising relay-sets individually connectedwithone of said stations, a relay-unit connected with! mon to all said connecting relays-in an idle re-'- laygroup and also -for-=- connecting said contact -ih'-'a' callingstation; which contact is connected tdi the w-in'ding of said connecting relays, tothe other terminal of said source of current, the con- -ne'cting :relayof said selected relay-group belongto -the-relay-setconnected with said calling .station thereby being actuated so that itlconmeets the combined transmitter and receiversof :sa'id calling station to the amplifier belongingto ;said-selected relay-group, and-keys in each-staztion 'forcalling any of the other stations; said lkeys actuating the relay-group selected byrsaid :rel'ay unit to connect .the transmitter and receiver of a called station to the amplifier belong- ,irrg to saidrelay-group. 4: In an intercommunicating zralityoi separate stations each comprising. a

combined transmitter and receiver, a source .of.

current, at least two amplifiers, a group of relays :for each ofsaid amplifiers, each of said groups comprisin'g relay-sets individually connectedwith one oi saidstationsya relay-unit connected with said- -relay-groups andwith said stations and adapted for selecting a relay-groupcnot occupied by a calha connecting'relay in each of said relaysets' the operating winding of which having one terminal connected to a contact in the respective station and theother terminal connected to a contact in saidrelay-unit,= which contact is common to all of said connecting relays in each relay-group, a holding winding on said connect,- ing relays, a' start contact in each station connectedwith said relay-unit, a cut-off relay and a 'control relay in'each station; a start key in each station for "connectingsaid start contact iria calling station via a cut-01f contact of said cut-off relay to one terminal of said source of current and for actuating said relay-unit to connect-said startcontact 'to said contact common to all said connecting relays in an 'idle relay-group-and for'connecting said contact in said "calling station which contact is connected to the winding of said connecting relays, via another "cut-off contact of said cut-off relay "to theother'terminal of said source of current and for energizingsaid control relay to energize'said c'ut oflrelay'which again cuts off the connection between "on "the one hand isaid start contact and said contact connected to the winding of said connecting relays and on the other hand said source of current, the actuationof the start key'ina calling station thereby causing transmission of a short impulse only to the operating winding of the connectingrelay in' said selected relay-group, the said relay then being held by its holding winding, the actuation of said connecting relay causing the connection of the .combined transmitter and. receiver of said calling station to the amplifier belonging tosaid, selected relay-group, and keys in each station for calling any of the other stations, said keys actuating the relay-group selected by said relayunit to connect the transmitter andreceiver of acalled station to the amplifier belonging to said relay-group. .l .t. ,4

5."In annintercommunicating system, a plurality of separate stations each comprising a combined transmitter and receiver, asource of current, at. least two amplifiers, a group of relays for eachlof said amplifiers, each .of said groups .comprising relay-sets individually connected with one of said stations, a relay-unit connected with said relay-groups andiwith said .startion's andadaptedfor selecting a relay-group system, a plunot occupied-by a call, a connecting relay inea'ch oi saidrelay sets-the operatingiwinding of which having one terminal connected to a contacttin the-respecti vestation and-theother terminal connectedtdacontact insaid relay-unit, which contact is-common-toall of said connecting re.- lays in each relay-group a start. contact in each station connected with said relay-unit, said start Contact's in'all stationsbeing mutually con-nected, a -startkey in each station for connecting said startcontactin a callingstation to one terminal of saidlsource' 'oicurren't and for actuating said relay unit to connect said start contact. to said contactic'ommon to all said connecting relays in an -.idleir.elay.-group and alsovfor connecting said contactsina a calling station, which .contactv .is connected to, the winding of said connecting .re lays atoethew'othersterminal of said source of current; the connecting relay of said selectedrelay-group .belonging to the .relay-setconnected withsaid calling station thereby being actuated soithat itlconnects the combined transmitter and receiver.ofesaidlcalling station to the amplifier belonging to said selected relay-group, and keys in each istation. for. calling any of the, other stations saidkeys actuating the relay-group sel'ectedbyssaid relay-unit to connectthe transmitterlandsreceiyerwof a called station to .the amplifier. belonging .to said relay-group. fie In van ,intercommunicating system, a. pluralityaof separatestations. each comprising ,.a combined ,transmitter andreceiver, a source-sot current, at least. twoamplifiers, a group of relays ,foneach v.ofsaid amplifiers, each of said groupsscomprising relay-sets individually connectedswith-aoneflof said stations, anda release relay. arelaycunitrcomprisin a number of relay sets equal. ,to..the number of relay-groups, each, last-mentioned relay-set comprising two relays,;';,one=-controlling the energization of the other, and; being provided with an operating winding .connectedlbetween a group contact ,connectedwithacorresponding relay-group, and one terminallofithesourceof current and provided with,a,holdingewinding, a start key in each stationv fmhenergizationof said control relays which then are held I,by,.its.,ho1ding windings which aiterssaid eenergization.v are connected, between onewtfirminal of said source of current andam others group contact ,connected with said corresponding relay-group, the last mentioned group contactbeing connectedwith the other terminal ofsaid. sourcesofhcurrentivia a contact of the release ,relaybf. ,said group, the other relaystof said .relayrsetsein the relayeunit then selecting aniidle-arelayi. group and energizing the latter tow-connect ethencombined transmitter and receiver of a calling station .to the amplifier. belqnginghto, said relay-group, and keys in each stationior -calling any .of the other station-ssaid keys actuating'th'e relay-groupselected by said relay-unitato, connect the transmitteriandv receiverofa calledstation to. the amplifier belongingto, said relay-group.

,Inan, intercommunicating system, a pluraJity.- of;,separate.,stations each comprising a combinedfltransmitter and receiver, a source.of current atleasttwoamplifiers, a group of relays; fonieach. of..said amplifiers, each of said groups. comprising relay-sets individually. con-v nected with one ofl.said stations, and a release relay, a relay-unit comprising a number of relaysets equal to the number of relay-groups, each last-mentioned relay-set comprising two relays, 0ne.cont1;olling;the energizationof .the other and :beingprovided. "with ganf' operating winding connected between fa group contact-connected with La corresponding,lerelay group, and one terminal l'of the source 50f current and provided with a holding winding, a start key in each-station for energization of said control relays which then are held by its holdin windings which after said energization are connected between one terminal of said source of ourrenteand another group conof the relay which is without a make contact,

said normal and make contacts selecting an idle relay group which is energized to connect the combined transmitter and receiver of a calling station to the amplifier belonging to said relaygroup and keys in each station for calling any of the other stations, said keys actuating the relay-group selected by said relay-unit to connect the transmitter and receiver of a called station to the amplifier belonging to said relaygroup.

8. In an intercommunication system a plurality of separate stations each comprising a combined transmitter and receiver, a source of current, at least three amplifiers a group of relays for each of said amplifiers, each of said groups comprising relay-sets individually connected with one of said stations, and a release relay, a relay-unit comprising a number of relay-sets equal to the number of relay-groups, each lastmentioned relay-set comprising two relays, one controlling the energization of the other and being provided with an operating winding connected between a group contact connected with a corresponding relay-group, and one terminal of the source of current and provided with a holding winding a start key in each station for energization of said control relays which then are held by its holding windings which after said energization are connected between one terminal of said source of current and another group contact connected with said corresponding relaygroup, the last mentioned group contact being connected with the other terminal of said source of current via a contact of the release relay of said group, the other relays of said relay-sets in the relay-unit comprising a normal contact for connecting the first mentioned group contact via a calling station to one terminal of said source of power, which other relays in all said relay sets except one comprise also a make contact and in all said relay sets except two comprise a further make contact, said first mentioned make contacts being connected in series with each other and with the normal contact of the relay which is without a make contact, and said second mentioned make contacts being connected in series with each other and with the normal contact of the relay having a, normal contact and only one make contact, said normal and make contacts selecting an idle relay group which is energized to connect the combined transmitter and receiver of a calling station to the amplifier belonging to said relay-group, and keys in each station for balling any: of the other stations-said keys factu- Qating the.. relaygroup selected by said relay-unit to connect the transmitter and receiver of a called station to the amplifier belonging to said relay-group.

'9. :In an intercommunicating system, a plurality of separate stations each comprising" a .combined transmitterrand receiver, at least two "amplifiers, a group of relays for each of said ram- -plifiers, each of said groups comprising relaysets individually connected with one of said :startions, eachset being-provided with a connecting "relay having an operating and a holding winding, ha relay-unit connected with said relay groups and with said stations and adapted for selecting a relay-group not occupied by a call, a sstartkey in each'stationjfor operating said relay-unit to select an idle relay-group and for operating said selected relay-group to connect the combined transmitter and receiver of a calling station to the amplifier belonging .to said .relay group and keys in eachzzstation for-cal'ling any of the other stations, said keys actuating said connecting relay in the relay-set corresponding to a called station in said selected relay-group to connect the transmitter and receiver of said called station to the amplifier belonging to said selected relay-group.

10. In an intercommunicating system, a plurality of separate stations each comprising a combined transmitter and receiver, a source of current, at least two amplifiers, a group of relays for each of said amplifiers, each of said groups comprising relay-sets individually connected with one of said stations, each set being provided with a connecting relay having an operating and a holding winding and with an impulse relay controlling the energization of said connecting relay, the windings of said impulse relays being all connected in parallel to one terminal of said source of current, a relay-unit connected with said relay-groups and with said stations and adapted for selecting a, relay-group not occupied by a call, a start key in each station for operating said relay-unit to select an idle relay-group and for operating said selected relay-group to connect the combined transmitter and receiver of a calling station to the amplifier belonging to said relay-group and keys in each station for calling any of the other stations, said keys actuating said impulse relays which connect one end of the operating windings of said connecting relays in said selected relay-group to one terminal of said source of current, the connecting relay in which the other end of its operating winding by means of the key corresponding 1.0 a called station is connected to the other terminal of said source of current being energized, which energized connecting relay thereby connects the transmitter and receiver of said called station to the amplifier belonging to said selected relay group.

11. In an intercommunicating system, a plurality of separate stations each comprising a combined transmitter and receiver, a source of current, at least two amplifiers, a group of relays for each of said amplifiers, each of said groups comprising relay-sets individually connected with one of said stations, each set being provided with a connecting relay having an operating and a holding winding and with an impulse relay controlling the energization of said connecting relay, the windings of said impulse relays being all connected in parallel to one terminal of said source of current, a relay-unit connected with said relay-unit to select an idle relay-group and for operating said selected relay-group, to connect 5. the combined'transmitter and receiver of a calling station to the amplifier belonging to said relay-group, a calling relay in each station, in

which one end of the winding is connected to one terminal of said source of current and the other end via an open contact connected with the other iterminal of said source of current, said latter connection comprising a condenser limiting the 'time of current flow in said connection to the period of charging said condenser, and keys in each station for calling any of the other stations, said keys actuating said impulse relays which connect one end of the operating windings for said connecting relays in said selected relaygroup to one terminal of said source of current I and said keys closing said open contact so that the connecting relay which corresponds to the 12 key belonging to 8, called station is energized, which energized connecting relay thereby connects the transmitter and receiver of said called station to the amplifier belonging to said selected relay group.

KARL INGEMAR BERTIL LEGERTH.

REFERENCES CITED The following references are of record in the file of thispatent:

UNITED STATES PATENTS Number Name Date 1,356,256 Britten Oct. 19, 1920 1,647,606 Coggeshall Nov. 1, 1927 2,036,023 Curl Mar. 31, 1936 2,054,933 Frazier Sept. 22, 1936 2,110,358 Dreisbach Mar. 8, 1938 2,200,814 Wolak May 14, 1940 2,269,142 Campbell Jan. 6, 1942 2,269,143 Campbell Jan. 6, 1942 2,347,080 Campbell Apr. 18, 1944 

